Printing machines normally include a printing couple which has a number of cylinders and/or rollers such as impression cylinders, master or plate cylinders, blanket cylinders, ductor rollers, transfer rollers, oscillating rollers, form rollers, and the like. For instance, an ink fountain is disposed generally at the rear of the machine for feeding ink to the various rollers of the printing couple which transfers images to copy sheets. In such printing machines as rotary offset lithographic duplicating machines, a moisture fountain also is disposed adjacent the printing couple for feeding moisture to the printing couple. A number of rollers which generally can be termed "distribution" rollers are provided between the ink fountain and/or moisture fountain for distributing ink and/or moisture to the printing couple of the machine. The distribution rollers conventionally are mounted between spaced side frame plates of the machine framework.
One of the problems with ink feeding systems in machines of the character described above is the inability to effectively compensate for varying environmental conditions, such as varying temperature and/or humidity. It has been found that moisture content or "presence" in the immediate environment of a printing or duplicating machine may be the biggest problem area in maintaining quality printing. For instance, too much moisture in an inking system can "flood" the ink and cause emulsification. Even a 0.5-1.0 percent change in humidity can have a significant change in the ink flow characteristics of the machine. Consequently, an operator is constantly adjusting the ink fountain and/or moisture fountain of the machine in varying environmental conditions, because controlling the environmental humidity is very difficult if not impossible in a particular location. Yet, moisture control cannot be divorced from temperature control within the printing couple.
The moisture problem, above, in conjunction with the need for ink/water balance in conventional offset lithography has traditionally been the source of a multitude of problems for the offset printer. Variations in ink/water balance can cause emulsification of ink, as stated above, and can also lead to inconsistency in color, longer drying times, streaking problems as well as scumming and plugging of halftones.
An offset press operator must have a wide range of skills indeed to control all the complexities of offset lithography. Mechanical skill is required to understand and operate the functions of paper feed and delivery as well as register controls. Some artistic ability is necessary to interpret, match and maintain color. In addition, it also is necessary to have a basic understanding of chemistry in order to be able to understand and interpret the variables of ink/water balance. These variables include such things as water hardness, PH, conductivity, alcohol content, water take-up of ink and absorption of substrates.
Because of the various problems identified above, there is a definite contemporaneous trend to "waterless" printing processes or machines which eliminate the need for water in the printing process. By eliminating the need for ink/water balance, the waterless system changes the printing process from a chemical/physical process to a purely physical one, eliminating a large percentage of process variables as described above. The waterless system offers a shorter learning curve for press operators and greater ease of operation. Because there is no need to achieve ink/water balance at the start of a press run, a waterless press can roll up to color almost immediately. The system will normally achieve color in less than twenty impressions, thus giving the press operator nearly instant color communication. Response times to color changes are dramatically improved over conventional lithography.
Virtually any sheetfed press can be equipped to do waterless printing. Waterless plates are required. Waterless inks are required. And a control system to maintain the proper temperature is required for the waterless printing process. The control system normally includes a water circulation system through one or more points of the printing couple such as the plate cylinder or the ink "ball" or roller of the printing couple. A popular water circulation system circulates the water through one or more of the ink distribution rollers of the machine, such as an oscillating or vibrator roller. The system also includes water heater and chiller units, pumps, valving and appropriate conduits or piping. A temperature monitoring system is incorporated in the printing couple, such as at the plate cylinder surface, and a feedback system is provided to control the plate cylinder surface temperature by adjusting either water temperature or water flow to the vibrator roller(s). The bulk of the water circulation system, such as the water heater and chiller units, pumps, valving and the like normally are housed remote from the printing machine itself. Because of the remoteness of the control unit, pressure losses occur and which must be compensated for by the size of the water pump and piping. Thermal losses occur which must be compensated for in designing the size of the chiller/heater. There also is a control time leg which must be taken in consideration. Other problems include potential water leakage because of the piping and fittings required between the remote control unit and the printing machine. All of these problems are magnified in a zone control system wherein a plurality of printing machines or a plurality of printing couples within a large press, for instance, are controlled from a single control unit which is considerably remote from the machines themselves.
In many applications, it would be highly desirable to be able to integrate the various components of the temperature control system directly into the printing machine. However, in most machines there simply is insufficient room or inadequate space for the components. Even if some space is available, the space would require the components of the control system (heater, pumps, etc.) to be mounted in a high density manner which would make servicing of the control system extremely difficult if at all possible.
The present invention is directed to solving this myriad of problems by providing a unique system for mounting a temperature control system directly onto the printing machine as an integral part thereof, while allowing easy access to the components of the system, even easier access than is afforded by remote control units presently being used.